JPS5980186A - Rotor position detecting circuit for motor - Google Patents

Abstract

PURPOSE:To obtain a detecting circuit capable of readily generating a dense position signals exceeding the position code number of a position detector by displaying the rotating position of a rotor by the counted value of the fine rotating pulse from the position detector and a rough position code. CONSTITUTION:A normal rotation pulse PP and a reverse rotation pulse NP are outputted from a four times pulse generator 30 which inputs an A-phase pulse AP and a B-phase pulse BP from a pulse encoder (not shown). A preset data PC and a preset signal PS are outputted from a rise/fall detector 31 which inputs bits C1, C2, C4, C8 of position code IP from the pulse encoder. An up-down counter 32 set by data PD by a signal PS up counts the pulse PP, and down counts the pulse NP. The binary code of the code IP from a gray/binary converter 33 becomes more significant bit of the address of an ROM34 and the counted value of the counter 32 becomes less significant bit, and sintheta, costheta from the ROM34 are outputted through a D/A converter 35.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotor position detection circuit for a motor such as a synchronous motor, which detects the rotational position of a rotor, and particularly to a rotor position detection circuit for detecting the rotational position of a rotor such as a synchronous motor. The present invention relates to a motor rotor position detection circuit capable of generating a position code. .

A rotating field type synchronous motor consists of an armature as a stator and field poles as a rotor, and generates a rotating magnetic field by applying three-phase alternating current to the stator windings (armature windings). occurs,
The field pole is pulled by a rotating magnetic field to cause the field pole to rotate at the same speed as the rotating magnetic field, and compared to such a synchronous motor (RZ, DC motor), the speed control is complicated and the configuration of the control circuit is considered to be complicated. However, in recent years, a drive system that performs torque generation control equivalent to that of a DC motor has been developed, and its speed control of 1W has become easier.

In this drive system, if the phases of the armature current and induced electromotive voltage are controlled to be in phase (if the main magnetic flux and armature current are controlled to be orthogonal), torque generation control becomes equivalent to that of an IK-flow motor. To achieve this, detect the position of the field pole (that is, the phase of the main magnetic flux, and the induced electromotive force E (which is 90 degrees out of phase with the phase of l), and have a phase corresponding to the position. It is necessary to generate a current command and apply this current command to the armature windings of the synchronous motor.

Generally, in order to detect the position of this field pole, a pulse rotor is provided on the rotating shaft of the field pole (rotor), and the pulse rotor outputs a position code corresponding to the rotor's rotational position to detect the rotor's rotational position. configuration is widely used. This pulse rotor consists of a rotating disk on which position codes are arranged radially at predetermined angles, and a detector that reads these position codes.
The number of position codes that can be placed on a machine is limited by its resolution, and even if a high-resolution Gray code is used as a position code, it is said that there will be only a few hundred at most, and the accuracy of position detection is insufficient. Therefore, fine control was difficult.

Therefore, an object of the present invention is to provide a motor rotor that can easily generate a dense position signal that exceeds the number of position codes of a detector, regardless of the limit on the number of position codes due to the resolution of a detector for detecting the rotational position of the rotor. To provide a position detection circuit.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an overall block diagram of one embodiment of the present invention.

In the figure, reference numeral 1 indicates a rotating field type synchronous motor, and 2Il'i/Curse encoder, which is directly connected to the shaft of the synchronous motor 1 and generates various position signals.

This pulse encoder 2 will be explained in detail using the configuration diagrams of FIG. 2 and FIG. 3. noculus encoder 2
A code plate 26 is provided on a rotating shaft 20 that is directly connected to the shaft of the synchronous motor 1, and a light emitting element 22 such as a light emitting diode for reading the position signal of the code plate 23 and a light receiving element 21 such as a photodiode. is the code plate 26
d are provided facing each other, and an output circuit 24 is further provided.

As shown in FIG. 6, the code plate 23 includes a physiognomy track a1B phase track b, and a code track d consisting of four tracks.
are formed on concentric circles, and A phase and B phase tracks a
, b are rotating pulse trains (with a phase shift of π/21).
Incremental curves) occur when the cord plate rotates (turns are formed).

On the other hand, chord track d consists of 4 tracks.

Each track pattern is formed so that a different 4-bit position code (absolute code) is generated corresponding to each rotation angle of the code plate, and a gray code is used as the position code. 3 is a sine wave generation circuit which will be described later, and when the counter is set to KKL and the position code IP from the pulse encoder 2 is set, the human phase pulse AP and the B phase pulse BP from the FC pulse encoder 2 are set.
5ino value according to the counted value, C'OSθ
It outputs a value. .

7υ F/V that converts the pulse speed of the positive pulse train PP or negative pulse train NP from the sine wave generation circuit 3 into voltage.
It is a converter, and its output voltage is proportional to the rotational speed of the motor 1 and becomes the actual speed and pressure TSA.

8t is an operator circuit that calculates the difference (hereinafter referred to as speed error) El between the speed command voltage VCMD commanded from a speed command circuit (not shown) and the actual speed voltage TSAO (hereinafter referred to as speed error), and 9 is an operator circuit that amplifies the speed error ER to obtain the amplitude of the armature current. error amplifier that outputs IS;
10a and 10b are multiplier circuits that multiply the output of the error amplifier 9 and the output cosθ, sinθ of the sine wave generation circuit 6 to obtain two-phase current commands I, a (=Isssinθ).
, I□b (=lsecosθ), respectively. Reference numeral 11 denotes a 2-phase to 6-phase conversion circuit for converting a 2-phase signal into 3-phase signals, and has a circuit configuration as shown in FIG. That is, the 2-phase to 6-phase conversion circuit 11 includes two operational amplifiers OA1 and OA2 and ioKΩ resistors R8 to R4.
1, which has a resistor I of Ω at 578, and a resistor R6 of Ω at 5. Now, each resistor R.

If the value of ~R is determined as above and the wires are connected as shown, from the terminals Tu, Tv, Tw, tt
It will be output. And these lu, Iv,
iw (d-) This is a three-phase current command that has a phase difference of 2π15 from each other and is in phase with the induced electromotive force EO.

12a', 12b, 12c are command currents I
This is an arithmetic circuit that calculates the difference between u, Iv, 1w and the actual phase current, and each 411 command current Iu,
Iv, Iw and current transformer 15a.

Actual phase current I detected at 151, > , 15 c
au, Iav.

This is to calculate the difference in Iaw. i3a, 13b.

13C is a DC amplifier provided for each phase and amplifies the current difference between the phases, and 14a, 14b, and 14c are pulse width modulation/inverter circuits. Pulse width changei! J,v
Each of the l-cum-inverter circuits 14a, 14b, and 14c is
As shown in FIG. 5, a sawtooth wave generation circuit 5TSG generates a sawtooth signal STS'fc, and comparators COMu and COMv.

COM w, horn toge) N0T1~NOT, l,
Driver circuit engineer ~ I) I1, V, and inverter 14
is six powered ginger transistors Q1 to Q, and a diode D.
, -D. These are the pulse width modulation circuit 14
0, and each comparator COMu, COMv, C0Mw receives a sawtooth wave signal STS and a three-phase AC signal iu, respectively.
lv.

The interpupillary distance of iw is compared, and when iu, iv, and iw are larger than the value of 8TS, '1' is output, and when they are smaller, '0' is output. Therefore, if we focus on iu now, the comparator C
A pulse width modulated air current command iuc shown in FIG. 6 is output from OMu. That is, the pulse width is modulated according to the amplitudes of iu, iv, and iw.
, ivc,, iwc are output. Next, NOT gate N0T1~NOT,, driver circuit D■1~I
For JV6, these current commands iuc, ivc, iw
c into drive signals sQ+~SQ, and inverter 1
1 controls on/off of each power transistor Q, to Q6t constituting 41, and 142 is a rectifier circuit for DC power supply. 15a, 1jb', and 15c are current transformers for detecting phase currents.

Next, the operation of the circuit shown in FIG. 1 will be explained.

When the power is turned on, the position code IP of the pulse encoder 2 is input to the sine wave generation circuit 3, and the COSθ value is changed to the 5inQ value fl, , C, O1 accordingly.
A voltage corresponding to 9° sin θ is output. Thereafter, the speed command VCMD is given to the synchronous motor 1, three-phase AC is supplied, and when the synchronous motor 1 rotates, a human phase pulse AP and a B phase pulse B, P are generated depending on the rotation direction.
When the force pulse encoder 2 generates t, a counter counts this and outputs a sine wave S group θ and a cosine wave cos θ according to the rotor position θ along with the position code IP.

On the other hand, to rotate the synchronous motor 1 at a desired rotational speed Vc, a speed command voltage VCMD having a predetermined analog value is input to an addition terminal of an arithmetic circuit 8. Since the synchronous motor 1 is rotating at the actual speed Va ((Vc), F
Actual speed voltage T8 proportional to actual speed Va from /V converter 7
A is output, and this actual speed voltage T S A i is input to the subtraction terminal of the arithmetic circuit 8 . Therefore, the calculation circuit 8 calculates a speed error 1 which is the difference between the command speed Vc and the actual speed VaO, and inputs this into the error amplifier 9. The error amplifier 9 performs proportional-integral calculation as shown in the following equation.

Note that the calculation result Is of equation (2) corresponds to the amplitude of the armature current. That is, when the load fluctuates or the speed command changes, the speed error ER (=Vc=Va) increases, and the armature Ichikawa amplitude Is also increases accordingly. As Is increases, greater torque is generated, and this torque brings the actual speed of the motor to the commanded speed.

On the other hand, since the two-phase sine wave cos θ and cosine wave sin θ indicating the position θ of the field pole of the synchronous motor 1 are output from the sine wave generating circuit 3 as described above, the multiplier circuits 10a and 10b
I, a = Is * sin θ, 11b =
Is @ cos θ is calculated and the two-phase current command 11a is
, 11b is output. Next, 2-phase to 3-phase conversion circuit 1
1 performs the calculation shown in equation (1) to obtain the three-phase DC command Iu,
Output Iv and Iw, respectively. Furthermore, these Iu, Iv
, I to ■ are six-phase current commands in phase with the induced electromotive force EO of the synchronous motor 1 and IC.

After that, the three-phase current commands Iu, Iv, and Iw are sent to the arithmetic circuit 1.
At 2a, 12b, 12C, the phase current Iau of one prefecture,
Iav.

A difference is taken from Iaw, and the three-phase alternating current signals iu, iv, iw, which are the differences, are then amplified and sent to the comparators COMU of the pulse width modulation and inverter circuits 1da, 14b, and llc.

COMV, COMWKell addtlle. Each comparator COMU.

COMV and COMW are sawtooth wave signals STS, respectively.
The widths of the three-phase AC signals iu, iv, iw are compared, and the pulse width modulated three-phase current commands iuc, ivc,
Output iwc, non-gate N0T1~N O'r
, and driver DV, ~1] (1) Outputs inverter drive signals SQ+ to sQe through 6. These inverter drive signals sQi to S (each inverter 141
is manually applied to the base of each P1-to-transistor Q, ~Q, that constitutes, and each Howard transistor Q, ~Q
ot on 7/off f! tll tl(l l,, supplies three-phase current to the synchronous motor 1.

Thereafter, similar control is performed and the synchronous motor 1 finally rotates at the commanded speed.

Next, the configuration and operation of a sine wave generation circuit including a rotor position detection circuit according to the present invention will be explained.

FIG. 7 is a block diagram of one embodiment of the present invention, in which 3
0 is a quadruple pulse generation circuit, which generates four times the number of forward rotation pulses P for forward rotation from the human phase and B phase rotation pulses AP and BP.
31 is a rising/falling detection circuit which detects the rising/falling of each bit 01 to C8 of the position code IP, and generates four times the number of reverse rotation pulses NP in the case of reverse rotation. This is a 321d up-down counter that outputs preset data PD, brisset, and start signals PS of the counter, and the preset data PD is set by the preset signal PS of the rising/falling detection circuit 51.
33 is a gray/binary conversion circuit that counts up the forward rotation pulse PP or down counts the reverse rotation pulse NP.

64 is a read-only memory (ROM) that converts the position code IP (bits C1 to C8) into a binary code, and a sine wave,
Each digital value of cosine wave! 1θ value.

A gray/binary conversion circuit 33 stores the cose value.
The binary position code of is used as the upper digit of the address, the count value of the counter 32 is used as the lower digit of the address, and the corresponding sin θ value and cos θ value are read out, 65
is a digital-to-analog (DA) converter, and the ROM
, B4, the 5ino value and the coso value are converted into analog outputs and output to the multiplication circuits 10a and 10b (Fig. 1).

The above-mentioned quadruple pulse generation circuit 30 has a N O'I' circuit N1 and a flip-flop circuit F' for the human phase pulse A P.
F'1. li'F'2 is provided, and the B-phase pulse BP
For NOT circuit N2, flip-flop circuit F
3, FF4/bar is provided. Furthermore, a gate group circuit GC is provided which creates a forward rotation pulse PP or a reverse rotation pulse from the output of each flip-flop circuit FF 1 to FF 4 . ) ■ To explain this using the waveform diagram in Figure 8, assuming that the motor is rotating in the forward direction, the B-phase pulse BP is generated with a 290° delay from the A-phase pulse APK, and conversely, when the motor is rotating in the reverse direction, , the human-phase pulse AP is generated with a delay of 900 sec from the B-phase pulse BP. Therefore, as shown in the waveform diagram for forward rotation in Figure 8, the flip-flop circuit FF1-phase pulse An output that is in phase or out of phase with the AP is generated.

This output A1. A I is a flip-flop circuit F
' Delay by one clock with F2 and output A2. A2
becomes.

The same applies to the B-phase pulse BP, and the flip-flop circuits FFs and FF4 output B1, B1, B2.
.

B2 occurs. These eight outputs AI, AI.

A2, A2, B1, B1, B2, and B2 are manually input to the gate group circuits G and C to create a forward rotation pulse PP or a reverse rotation pulse NP. That is, the forward rotation pulse PP
is (A1・A2・81), (1・132 to A101
), (A1・A2 豐81), (Al・131・B2
), so four AND gates that take this condition are provided, and an OR gate that takes the logical sum of the outputs of the AND gates is provided, and the output of the OR gate is the forward rotation pulse PP shown in Figure 8. Therefore, the pulse is 4 times the human phase or B phase pulse AP, Bl'.On the other hand, when the motor is rotating in the reverse direction, the output A due to the human phase pulse in Fig. 8 is
1-A2. The phase relationship between the outputs 81 and B2 due to the B-phase pulse is created in the opposite manner, and four AND gates that take this condition are provided, and an OR gate that takes the logical sum of the outputs of these AND gates is provided. The output becomes the reverse rotation pulse NP, which is four times the human phase and B phase pulses AP and BP. Therefore, in the case of forward rotation, only the forward rotation pulse PP is output from the gate group circuit GC,
In the case of reverse rotation, only the reverse rotation pulse NP is output.

Next, the rise/fall detection circuit 61 described above calculates the position +it=
+-do I P each pitch) cl, C2, C4, CB
For IC, NOT circuit N5. N4. N5. N6. Front stage flip-flop circuit 1i'F5, FF7, FF
9, FF11. Post-stage flip flop 07 circuit FF6.
FF8. Each pin of 61 position codes IP provided in FF1o and FF12) C1, C2.

C4, C3iC each have four outputs Cs1. C shoulder, C
B2゜C82, C41, C4+, C42, C42, C
21, C21, C22° C22, C11, (11, CI
2, CI2 outputs 1, and the relationship between these four outputs is the A-phase pulse AP output N in Figure 8.
This is the same relationship as 1 to A2.

These 11 and 16 outputs C81 to CI2 are the gate group circuit G.
D is manually operated to create preset/soto data PD and prehit signal PS. First, the gate group circuit GD detects the point of change (rising/falling) of the position code IP. That is, as mentioned above, the output A1 of the four outputs 081 to 0828
~ Same phase relationship as A2 and f, C force 1 et al.

Therefore, it is sufficient to provide four σ) AND gates that meet these conditions. Also, the rising edge of each bit is (C81-CB
2) , ((11-Cv2) , (C21-022
), (C11-012), and it is sufficient to provide four AND gates that take these σ-) conditions.

The outputs of these eight AND gates are logically summed by an OR gate and output as a preset signal PS.

Furthermore, gate group circuit GD1. is before: r+1% F)
The direction of rotation of the motor is detected from the 16 human valves jCF11 to Cv'2, and if it is forward rotation, it will indicate "oooo", and if it is reverse rotation, it will indicate "1".
The circuit that outputs the 111" burino set data is 41".
3. Use the /i sclade change for this.

That is, the gray codes are arranged as shown in the following table.

Table Therefore, if forward rotation is the increasing direction of Nll and reverse rotation is the decreasing direction of Na, then the change in forward rotation from 0000" to 10001" is 1d, the current position code is "0000", and the CI [,! , = and a rising edge occurs, so the condition (CI32-C42・C22・C12×C1
1.Cl2). Similarly, the positive rotation change from 0001"' to "0011" is also a case where the current position code IP is "'0001" and a rising edge occurs at bit C2, so the condition (C82-C42・C22・C
12X, C21/C22). Thereafter, 16 conditions are met in the same manner, whereby forward rotation can be detected and a forward rotation direction pulse is output. Therefore, 16 AND gates that take each of these conditions are provided, and an OR gate that takes the logical sum of the outputs of these AND gates is also provided, and the output of the OR gate (forward rotation direction pulse) is used to calculate oo
If a circuit is provided to generate the preset data PD of oo', it will detect the forward rotation and generate the reset data oooo.
” can be output. Conversely, in the case of reverse rotation, “oo
What is the change from oi″′ to “0000”?

Since the current position code is "0001"' and a falling edge occurs at bit C1, the condition (C82・m
l・roi・Cl2XC11・Cl2),
Similar to the above-mentioned forward rotation, 16 conditions are set, and 16 AND gates corresponding to these conditions, 1 OR gate, and a circuit that generates '1111' as preset data FD are provided, and fl, :ql' is good. ,.

The above uses changes in the Gray code]1. If the position code is a binary code, it can be similarly realized using changes in the binary code.

Next, the operation of the configuration shown in FIG. 7 will be explained. First, if the motor rotates in the forward direction, 1. Then, a forward rotation pulse PP is generated, and the counter g2id: it is the turn to count up this. On the other hand, the position code IP is input to the rising/falling detection circuit 31, and a changing point (rising, rising/'falling) is detected, a preset signal PS is generated, and a positive Jjil signal is generated every time this changing point occurs. The rotation direction pulse is output and as preset data PD" o o o
o'' occurs. The counter 32 calculates the value of this invariant point.
(), the preset data P D is preset to "0000", and thereafter the next change point is detected (preset signal P
Count up the forward rotation pulse 1) P until S occurs). This crying code TP is converted to the position code 1-I of the piston by the high-nolly conversion circuit 63.
It is converted to P, and the digit and l- of the address of the ROM 54 are manually inputted to 1 (, 0M5a, 7, and the count value of the f counter 32 is 1d. The lower digit of the address is input to the CROM 34, and this combination determines the correspondence of the ROM 34. address si
nθ value and cosθ value are read, '11. Ru.

Therefore, the address given to the ROM 34 is twice that of the case where only the 14th place code I'P is used (n is the number of bits of the counter 32), and a finer-grained address can be generated accordingly. This sin θ value, cos θ value [DA converter 35
is converted into analog sin θ and cos θ and output. Therefore, as shown in the operation explanatory diagram of FIG. 9, the analog sin θ or COS θ is a smooth 7
becomes. When the motor is rotating in the reverse direction, a reverse rotation pulse NP is generated from the quadruple pulse generation circuit 30, and the rising/
The fall detection circuit 31 generates "1111" as preset data PD every time the 7' IJ set signal PS is generated. The counter 32 counts down the reverse rotation pulse NP until the preset data PD "1111" is preset 11 every time the preset signal PS is generated, and thereafter until the next preset signal PS is generated. Subsequent ROM5a
Since at1/s of is the same as in the case of forward rotation described above,
Explanation will be omitted.

As explained above, according to the present invention, a counter is provided to count the minute rotational pulses from the detector, and the rotational position of the rotor is displayed based on the rough position code from the detector and the count value of 1 kunta of force. This has the effect of displaying detailed rotor position even if the position code is rough.
In particular, since the number of actual position codes is limited due to resolution, the present invention r1, which can output position codes several tens of times larger than the actual 11t hood, is extremely useful for precision control of motors. In addition, since this can be achieved using a pure circuit without changing the conventional detector, the configuration is simple and the control and wholesale is easy.

Although the present invention has been explained using one example, the present invention is not limited to the above-mentioned example, and various modifications can be made in accordance with the gist of the present invention, and these are excluded from the scope of the present invention. Then 7(tha.

[Brief explanation of drawings]

@Figure 1 is a block diagram of an embodiment of civil engineering invention, Figures 2 and 3
The figure is an explanatory diagram of the pulse encoder configured in Figure 1, Figure 4 &
21 Figure 1 is a block diagram of the two-phase to three-phase conversion circuit configured as shown in Figure 1. Figures 5 and 6 are explanatory diagrams of the pulse width modulation/inverter circuit configured as Figure 1. Figure 7 is the rotor position according to the present invention. FIG. 8 is a detailed block diagram of the detection circuit, FIG. 8 is an explanatory diagram of the main part operation of FIG. 7, and FIG. 9 is an explanatory diagram of the operation of sine wave generation according to the present invention. In the figure, 1...Synchronous motor, 2...Pulse encoder, 6...Sine wave generation circuit,! IO...4 times the pulse generation circuit, 31... Changing point detection circuit, 52... Counter, 34... Read only memory. Patent applicant Tsuji, patent attorney representing FANUC Co., Ltd. 2 people not awarded

Claims (2)

[Claims] (1) In a rotor position detection circuit of a motor that outputs a position signal corresponding to the rotational position of the rotor of the motor, the circuit is provided on the rotational shaft of the rotor and generates a position code corresponding to the rotational position of the rotor. It has a detector that generates a rotational pulse every predetermined rotation of the rotor, and a counter that counts the rotational pulse, and displays the rotational position of the rotor σ) based on the value of the counter between the position codes. A rotor position detection circuit for a motor. (2) A change point detection circuit for detecting a change point of the position code is provided, and the counter is preset by the detection output of the change point detection circuit. Motor rotor position detection circuit.